Smoking damages sperm and makes them less likely to fertilize an egg. This means that Rodney is less fertile than another male who does not smoke. This could make it more difficult for Rodney and Lisa to have children if they chose to. This creates second hand effects as well since the second-hand smoke could effect Lisa's fertility as well. Any embryos that they were able to create would be less likely to survive than someone who does not smoke. In other words, the chances of miscarriage are higher.
